A manure spill on a large Brown County dairy farm last week has caused the Wisconsin Department of Natural Resources to issue an advisory to local residents to be careful when using their drinking water.

The agency says 100,000 gallons of manure was released accidentally on March 13 at the James Kroll Farm when a valve was left open by one of the farm's workers. The incident happened in the town of Humboldt.

"The DNR and county health department advise the public that the water in the stream might not be safe for people or pets," the DNR said in a statement, adding that surface water samples are being taken to monitor water quality impacts.

DNR officials say some of the waste has reached School Creek, which is a tributary of the Kewaunee River.